Operator platforms and cabs for vehicle such as trucks, earthmoving vehicles, and the like are often mounted directly over the engine, transmission, hydraulic system, and other vehicle components. To permit access to these areas for servicing or repairs, operator cabs are often pivotally mounted on the vehicle frame to facilitate raising the cab from a substantially horizontal operating position to an upwardly tilted position exposing the vehicle components.
Operator platforms and/or cabs on earthmoving equipment are also typically equipped with roll-over protective structures (ROPS) or roll bars generally enclosing the operator platform. The ROPS may also include removable enclosure panels mounted on the ROPS forming compartments for the protection of the operator and the controls against the weather. To obtain sufficient exposure of the vehicle components, it is often necessary to raise or tilt the compartment and platform, or cab unit, past an overcenter position where the center of gravity of the compartment is located directly over the pivot axis.
In the past, hydraulic actuating systems or mechanically operated jacks have been employed to tilt pivotally mounted operator cabs. Prior art systems of this type are disclosed in U.S. Pat. No. 3,831,999 issued to Sonneborn, and U.S. Pat. No. 4,053,178 issued to York et al. While such tilting mechanisms have gained wide acceptance, they are subject to certain limitations. For example, the nature of the hydraulic system of the vehicle is such that fluid trapped in certain parts of the system prevents motion in one or both directions of the actuator, which interferes with the vehicle suspension. Thus, a more complicated and costly suspension system is required to overcome this problem.
Other cab tilting mechanisms are also known. One known prior art cab tilting mechanism includes a cab which is normally mounted to the vehicle by a plurality of mounting structures which include threaded fasteners or mounting bolts. The mounting bolts permit the cab to be releasably mounted on the vehicle frame. The mounting structures also include rubber isolation mounts to isolate vibration transmitted to the cab. The hinge structure includes a first hinge member hingedly connected to a second hinge member. The first hinge member is permanently mounted on the frame of the vehicle. The second hinge member is permanently mounted on the cab of the vehicle. To tilt the cab, the mounting bolts of the mounting structures are first removed. Once the mounting bolts are removed, the cab can then be tilted, such as for example, to permit access to areas underneath the cab. Although this type of mounting permits the cab to be tilted to vehicle frame, forces acting on the cab, such as from a rollover or other types of impacts, can bend or otherwise damage the hinge structure, thereby affecting the operation of the hinge members and detrimentally affecting the cab and vehicle frame mounting structures.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative to the prior art in the form of a releasable operator cab tilting apparatus.